Pin table

ABSTRACT

Positioning apparatus for use with a machine tool such as a drill press or the like. The positioning apparatus comprises a body frame having a viewing window therein; means for enabling the pin table apparatus to be moved so that the workpiece can be placed at said selected location; and a sighting mechanism for locating the predetermined template position. The sighting mechanism includes a pair of reflective surfaces that are spaced apart and are supported by the body frame, one of the reflective surfaces being visible through the viewing window, with the other reflective surface being optically aligned therewith and being movably supported within the body frame. These reflective surfaces facilitate locating a predetermined template position for positioning the pin table apparatus and workpiece at the location corresponding thereto.

U United States Patent [151 3,635,566 Caroli 1 Jan. 18, 1972 [54] PIN3,036,493 5/1962 Mottu et al. ..356/l64 Inventor: halo Cam", westmount'Q Canada 3,376,764 4/1968 Schardt ..77/64 [73] Assignee: DBM IndustriesLimited Primary min -R nald L. Wibert Assistant Examiner-.l. Rothenberg[22] Filed: Dec. 9, 1969 App]. No.: 883,385

[] Foreign Application Priority Data Mar. 25, 1969 Canada ..046,695

[52] U.S.Cl ..356/170,33/1 L, 356/172, 408/ [51] Int. Cl. ..G0lb 11/26[58] Field ofSearch ..77/64;356/170, 156, 172, 164, 356/; 33/125 A, 1 L;408/70 [56] References Cited UNITED STATES PATENTS 2,109,849 3/1938Price ..356/172 2,412,017 12/1946 Taylor et al. ....356/ 2,368,4321/1945 Turretfini ..356/l70 Attorney-Cushman, Darby & Cushman [57]ABSTRACT Positioning apparatus for use with a machine tool such as adrill press or the like. The positioning apparatus comprises a bodyframe having a viewing window therein; means for enabling the pin tableapparatus to be moved so that the workpiece can be placed at saidselected location; and a sighting mechanism for locating thepredetermined template position. The sighting mechanism includes a pairof reflective surfaces that are spaced apart and are supported by thebody frame, one of the reflective surfaces being visible through theviewing window, with the other reflective surface being opticallyaligned therewith and being movably supported within the body frame.These reflective surfaces facilitate locating a predetermined templateposition for positioning the pin table apparatus and workpiece at thelocation corresponding thereto.

10 Claims, 4 Drawing F igures PATENTEIJ JAN 8 m2 SHEET 2 0F 4 TITPATENTED JAN1 8 I972 SHEET ll 0F 4 PIN TABLE This invention relates topositioning apparatus in the broad sense, and more especially topositioning apparatus adapted for use with machine tools such as drillpresses, milling machines and the like.

The positioning apparatus is adapted to support a workpiece and isusually mounted on a worktable of the machine tool in question. Wheneverit is desired to effect certain machining operations to the workpiece,an operator mounts the same onto the positioning apparatus, togetherwith an apertured working template that is of a predetermined form orshape. The position of the apertures in the working template would beused to define the location at which a particular machining operationwill be carried out on the workpiece. Since the ways in which a workingtemplate is commonly used are well known in the art, it is believed tobe unnecessary to describe these ways in greater detail at this time.

It will be recognized that various types of positioning apparatus areknown in the art, however, these frequently have some deficiency whichdetracts from the overall efficient operation of the apparatus. InCanadian Pat. No. 722,929 (Schardt) issued Dec. 7, I965, there isdescribed a positioning apparatus which features the use of compressedair or gas to provide a relatively friction-free bearing surface orcushion on which the apparatus rides whenever the operator wishes tomove the same to place the workpiece at a selected one or other of thelocations where some machiningoperation is to be done to the workpiece.This patent also describes the use of a vacuum to effectively hold orlock the positioning apparatus in the selected location.

Another type of position apparatus, or pin table" as such apparatus issometimes called, is illustrated in Canadian Pat. No. 575,892 (Meyer)issued May l2, I959. That patent describes the use of preformed stripsthat coact with feeler means to actuate a rather cumbersome drivemechanism. This drive mechanism effects final positioning of theworkpiece to the selected location.

In either of the types of positioning apparatus noted above, there isextra equipment required, and such equipment tends to add to thepotential sources of mechanical or electrical failure. Moreover, suchprior art apparatus also tends to be somewhat restricted in use, in thatit is more or less tied down to operation in one location because of theaccessory equipment associated with it.

It is an object of the present invention to provide an improvedpositioning apparatus which is easy to operate, permitting the operatorto visually locate a predetermined position on a working template. Thus,the operator does not have to rely only upon a sense of feel, or to movethe apparatus about blindly in attempting to locate the desired templateposition.

It is another object of the present invention to provide an improvedpositioning apparatus of relatively few component parts, thus increasingthe reliability thereof and making the positioning apparatus relativelyeasy to manufacture.

These and other objects and features may be obtained according to abroad fonn of the present invention, wherein there is providedpositioning apparatus for use with a machine tool such as a drill pressor the like, and being adapted to enable placing a workpiece supportedthereon at a selected location corresponding to a predetermined positionon a working template also supported by the positioning apparatus, suchthat the workpiece can be machined as required at said selectedlocation, the positioning apparatus comprising; a body frame having aviewing window therein; means for enabling the positioning apparatus tobe moved so that the workpiece can be placed at said selected location;and a sighting mechanism for locating the predetermined templateposition, including a pair of reflective surfaces that are spaced apartand are supported by the body frame, one of the reflective surfacesbeing visible through the viewing window, with the other reflectivesurfacebeing optically aligned therewith and being movably supportedwithin the body frame to enable locating the predetermined templateposition for positioning the apparatus and workpiece at the locationcorresponding to said predetermined template position.

In a more preferred form the present invention provides pin tablepositioning apparatus for use with a machine tool such as a drill pressor milling machine, for example, and being adapted to enable placing aworkpiece supported thereon at a selected location corresponding to apredetermined position on a working template also supported by the pintable positioning apparatus, such that the workpiece can be machined asrequired at said selected location, the pin table positioning apparatus,comprising; a body frame supported on a workta ble provided on themachine tool and having a viewing window therein; a lifting mechanismfor lifting and lowering the body frame from and to engagement with theworktable to enable moving the pin table positioning; apparatus forplacing the workpiece at said selected location; and a sightingmechanism for locating the predetermined template position, including apair of reflective surfaces that are spaced apart and are supported bythe body frame, one of the reflective surfaces being visible through theviewing window, with the other reflective surface being opticallyaligned therewith and being movably supported within the body frame toenable an operator to visually locate the predetermined templateposition and subsequently position the pin table positioning apparatusand the workpiece at the selected location corresponding to saidpredetermined templateposition.

One specific embodiment of the present invention will now be describedbelow, by way of example only, with reference being made to theaccompanying illustrative drawings, in which;

FIG. 1 is a top plan view of one embodiment of a positioning apparatusaccording to the present invention;

FIG. 2 is a bottom plan view of the positioning apparatus of FIG. I, andshows the positioning apparatus from the bottom thereof;

FIG. 3 is a side elevation view taken. in section along line 3-3 of FIG.2, and showing the positioning apparatus in a raised position in whichit can be moved. about on the worktable;

FIG. 4 is a side elevation view taken in section along line 44 of FIG.2, and showing the positioning apparatus in a lowered or operativeposition wherein machining operations can be carried out on theworkpiece being supported on the positioning apparatus.

Tumingnow to the figures, the numeral I designates the pin tablepositioning apparatus overall. With particular reference to FIGS. 3 and4, the pin table I includes a lifting and lowering mechanism 50, asighting mechanism 100, and associated with pin table 1 is a lockingmechanism mounted in a worktable coverplate 152 that is part of themachine tool (not shown) with which the pin table is being used.

The pin table 1' comprises a body frame 10 having a generallyrectangular, dished-out interior cavity 12. A plurality of carefullymachined sets of guide channels 14 of generally T-shaped cross sectionare provided in the upper surface 16 of the body frame 10. The guidechannels 14 are generally equally spaced apart and extend parallel toone another. In other words, these sets of guide channels 14 aremutually parallel to one another. It is well known in the art that suchsets of guide channels function to enable a workpiece to be adjustablysecured to the pin table 1.

The body frame 10 is also formed with a viewing window I8 having asupporting frame 20 which is fastened by means of screws 22 or the liketo the body frame l0. A window 18 of glass, or transparent plastic orthe like is mounted in the supporting frame 20. In accordance with thepresent invention, an operator can look through the viewing window 18and by means of a pair of reflective surfaces 102 and 104 of highlypolished metal, mirrors or the like can visually locate a predeterminedposition on a template 24. The template 24 is attached to the body frame10 as shown in FIGS. 2 and 4 by means of fastening screws 26, or thelike. A pair of adjustable alignment screws 28 are also attached to thebody frame in order to enable the operator to mount the template 24 in apredetermined orientation relative to the pin table 1, and inparticular, relative to the guide channels 14.

As previously described, the body frame 10 is formed with an interiorcavity 12, with the peripheral wall portions thus provided on the bodyframe forming a seating or table-engag ing surface 36. This seatingsurface 36 is delimited interiorly thereof by a shoulder 34 with the pintable 1 thus being effectively limited to engagement with the work table152 along the peripheral wall portions thereof. It is to be noted fromFIGS. 2 and 3, that the wall portions and the seating surface 36 areprovided near the corners of the pin table 1 with slightly elongatedbore holes 32 which receive leg portions 58 of the lifting and loweringmechanism 50. It is also to be noted from FIG. 3 that the top innersurface of the body frame 10 is further recessed at 30 and 30 (FIG. 4)to accommodate other parts of the lifting and lowering mechanism 50.

As may be seen in FIG. 2, the lifting and lowering mechanism 50comprises two identical assemblies mounted on opposite sides of the bodyframe 10. These identical assemblies are operatively interconnected andsimultaneously actuated by means of a shaft 74 which is common to bothassem blies and which is provided at both ends thereof with actuatinghandles 76. Although the following description is with referencespecifically to only one of these two assemblies, it is to be understoodthat the same description applies to the other, equally well. FIG. 3shows one assembly of the lifting and lowering mechanism as comprisingmain supporting members 52 and 54, each being pivotally mounted on thebody frame 10 by means of main pivot pins 56. These two main sup portingmembers 52 and 54inelude tongue portions 52A and 54A which overlap oneanother. A leg section 58 is integrally and substantiallyperpendicularly connected to each of the main supporting members 52 and54. To facilitate moving the pin table I easily, a foot portion 60integral with the leg sections 58, is provided with a ball roller, acastor or the like. By means of such a foot portion 60, the pin table 1can be rolled along over the surface of the coverplate 152 of theworktable 152' with comparatively little effort.

It will be seen from the drawings that the overlapping tongue portions52A and 54A have a semicircular periphery and are joined together by acommon pivot pin 62. The pivot pin 62 enables relative rotationalmovement to occur between the main supporting members 52 and 54. Thepivot pin 62 is rotatably mounted in a connecting block 64 and extendsthrough slots (not shown) in the tongue portions 52A and 54A. It will beevident from the manner in which the main supporting members 52 and 54pivot in opposite directions, that the slot in tongue portions 52A and54A will be somewhat larger than the diameter of pivot pin 62. Theconnecting block 64 serves to anchor one end of a tension cable or strip68 that is connected thereto by fastening screws 66 or the like. Thistension cable or strip 68 is preferably made of steel or other materialhaving considerable strength, and is connected at its other end byscrews 70 to a winching drum 72. This winching drum 72 is carried on theshaft 74, and as previously mentioned, this shaft extends exteriorly ofthe body frame 10 on opposite sides, and is provided with actuatinghandles 76. In order that the tension cable or strip 68 exerts a liftingforce to the overlapped tongue portions of the supporting members 52 and54 in a substantially vertical direction (relative to the work table152), an idler pin 78 is mounted in the body frame 10.

FIG. 3 indicates that the weight of the pin table 1 and workpiecethereon is transferred through main pivot pins 56 to the lifting andlowering mechanism 50 and hence through foot portions 60 to thecoverplate 152. Moreover, it will also be evident that because there isno counter force to the moment developed by the weight of the pin table1 acting through foot portions 60 and hence about the axis of main pivotpins 56, that the normal rest position of the pin table is down, and incontact with the coverplate 152. Similarly, the nonnal rest" positionfor the lifting and lowering mechanism 50 is that shown in dotted linesin FIG. 3. When it is desired to move the pin table 1, the operatormerely grasps the actuating handles 76 and turns the same, thus causinga lifting force to be applied to the tongue portions of the mainsupporting members 52 and 54 of the lifting/lowering mechanism 50 hencecausing the same to be pivoted counterclockwise and clockwiserespectively, as seen in FIG. 3. The pin table I and workpiece carriedthereon are then moved to the next selected location at which a certainmachining operation is to be performed on the workpiece.

As previously indicated, when an operator wishes to position orreposition the pin table 1, he can look through the viewing window 18,and via the reflective surfaces 102 and 104 look down onto the template24. As may be seen particularly in FIG. 4, the reflective surface 102 isfixedly attached to a supporting shaft 106 which is pivotally mounted inthe body frame 10. One end of the supporting shaft 106 extends to theexterior of the body frame 10 and is provided with an actuating handle107, as may be seen in FIG. 1. Manipulation of the actuating handle 107by the operator will effect pivotal adjustment of the reflective surface102 in order to accommodate difierent lines of sight from the operatorthrough the viewing window 18 and onto the reflective surface 102. Thereflective surface 104 is fixedly mounted against rotational motionthereof in order that a line of sight from the reflective surface 102will always be reflected from the surface 104 directly downwards ontothe template 24. The reflective surface 104 is, however, horizontallyadjustable in order to enable the operator to move the same and passover and scan the template 24. The reflective surface 104 is fixedlyattached to a supporting block 108 by means of fastening screws 110 orthe like. The supporting block 108 is provided with two bore holesextending therethrough, with one of such bore holes being adapted toreceive a supporting shaft 112 while the other bore hole is adapted toreceive one end of an actuating rod 113 that extends exteriorly of thebody frame 10 and has a handle I13 thereon. The actuating rod 113 issecured against motion relative to the supporting block 108 by means ofa setscrew 114 or the like. In order to permit horizontal adjustment ofthe reflecting surface 104, the supporting block 108 is slidably mountedon the main supporting shaft 112. Preferably, there will be norotational movement of the reflective surface 104 relative to thesupporting shaft 112, and therefore, such shaft will be square orrectangular in cross section, or it may be provided with a rib orgroove, to cooperate with a complementary structure in the bore hole ofthe supporting block 108, i.e., in a tonguein-groove" manner. A secondsupporting shaft may be provided to support the opposite end ofreflective surface 104. The reflective surfaces 102 and 104 aregenerally of an elongated rectangular shape, and afford the operator thepossibility of looking down directly at the surface of the template 24over a substantial portion of the area of the template. At least onesource of illumination in the form, for instance, of a fluorescent light116 will normally be provided within the interior cavity 12 of the bodyframe 10, with such a source of illumination being controlled by meansof a switch 118 provided exteriorly of the pin table 1.

It is common that a template is usually provided with apertures, boreholes, or other deformations of a similar kind to enable some type ofsensing mechanism to detect the same and be responsive thereto. In thepresent instance, the template 24 is provided with apertures 25, withsuch apertures being located in the template according to apredetermined plan or layout related to the workpiece in question. Theposition of these apertures 25 correspond to selected locations on theworkpiece being carried by the pin table 1, at which locations certaindesired machining operations on the workpiece are to be carried out.Both the workpiece and template are located by a common dowel pin.

The locking mechanism that is specifically illustrated in FIG. 4, isadapted to be received in a guide channel 154 in the work table 152' andcoverplate 152. The coverplate 152 serves to enable the pin table 1 tobe moved about by preventing the foot portions 60 from falling into theslots, channels or apertures normally found in the work table 152. Thelocking mechanism 150 includes a locking pin 156 which is biased bymeans of a compression spring 158 outwardly, to be received within oneof the template apertures 25 when the pin and aperture are brought intoalignment. The locking pin 156 is bored from one end thereof, with thecompression spring being positioned within this bore hole. A backing pin160 is l positioned within a pair of diametrically opposed slots 161provided in the sidewalls of the locking pin 156. It will be noted fromFIG. 4 that the backing pin 160 is rigidly secured to that portion of acover piece 162 which extends partly down into the guide channel 154.The cover piece 162 is fastened to the coverplate 152 by means of screws164 or similar fastening means. It will be apparent from the way inwhich the locking pin 156 is mounted, that this pin will have reciprocalvertical movement to effect locking engagement of the pin 156 in anaperture 25 of the template 24.

It will therefore be recognized that when it is desired to place theworkpiece at a preselected location corresponding to a predeterminedposition on the template 24, for effecting certain machining operationsto the workpiece, the operator will use the sighting mechanism 100 tolocate the predeter mined position defined by a particular aperture 25.Having located that aperture, he will then operate the lifting andlowering mechanism 50 to a lift the body frame 10 free of the coverplatetable 152. The operator will then move the pin table 1 and the workpieceuntil the locking pin 156 becomes aligned with the particular aperture25 selected and is received therein to effectively hold or lock the pintable 1 at the selected location. It will be recognized, of course, thatthe workpiece will have initially been positioned on the body frame 10by means of the common dowel pin to be compatible with the orientationof the template 24. [n this way, as soon as the template 24, is broughtinto position and locked there, by means of the mechanism 150, theworkpiece will similarly have been placed into the correct location toenable the desired machining operation to be carried out on thatparticular portion of the workpiece. It will also be apparent that ifthe template 24 were manufactured from a transparent or at leastsemitransparent plastic or similar material, the operator could locatethe predetermined template position defined by a particular aperture 25and move the pin table 1 to position the workpiece to a locationcorresponding exactly thereto, with a minimum of groping about. This isin contrast to some known devices in which very little or no indicationis visually obtainable of where the predetermined template position isrelative to the locking pin 156. It is to be recognized that if thetemplate is of a transparent plastic and highly accurate positioning isrequired in an operation carried out a very large number of times, somewear problems may arise. it is likely that for pure ly strength anddurability reasons, steel templates will be used where high accuracy iscritical. This situation will be apparent to those familiar with thisart. lt will therefore be seen that the present invention provides a pintable positioning apparatus which is relatively simple and easy tooperate, while simultaneously enabling the operator to see almost all ofthe reference points being used to bring the pin table and workpiece toany selected location.

The foregoing disclosure has described but one specific embodiment ofthe present invention, and has indicated some of the modifications whichmay be made without departing from the spirit of the invention.Additional modifications may also be possible and it is comprehendedthat all such modifications and alternatives may be used in apositioning apparatus of the type contemplated herein without departingfrom the spirit of the invention defined in the appended claims.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:

1. Positioning apparatus for use with a machine tool such as a drillpress, a milling machine, or the like, to enable placing a selectedmarked location on a worktable such that the portion of said workpiececan be machined as required at said selected location, the positioningapparatus comprising:

a body frame having a viewing window therein, said body frame supportinga workpiece to be machined;

an apertured template mounted within said frame in fixed predeterminedrelationship with respect to said workpiece;

a sighting mechanism for locating a selected template aperture which isin said predetermined relationship to said selected workpiece portionincluding a pair of reflective surfaces that are spaced apart and aresupported by the body frame, one of the reflective surfaces beingvisible through the viewing window, with the other reflective surfacebeing optically aligned therewith and being movably supported within thebody frame to enable viewing the selected template aperture, and meansfor moving said body frame to a position such that the selected templateaperture overlies said marked location on said worktable when viewedthrough said sighting mechanism, whereby said selected portion of saidworkpiece is positioned to be machined.

2. The positioning apparatus of claim 1, wherein the other reflectivesurface is movably mounted on supporting guide means, and has actuatingmeans connected thereto for enabling an operator to move said otherreflective surface over the template, thereby to visibly locate theselected template aperture.

3. The positioning apparatus of claim. 1, wherein the means for movingthe body frame includes a lifting and lowering mechanism operable foreffecting disengagement of a major portion of the body frame from theworktable on which it is mounted.

4. The positioning apparatus of claim 3, wherein the worktable isprovided with a locking mechanism having pin means therein, the pinmeans being operative for engaging the selected template aperture toeffect holding the workpiece substantially fixed in place.

5. Positioning apparatus for use with a machine tool such as a drillpress or milling machine, for example to enable placing a selectedportion of a workpiece supported thereon above a selected marked locatedon a worktable, such that the portion of said workpiece can be machinedas required at said selected location, the position apparatuscomprising:

a body frame supported on the worktable provided on the machine tool,the body frame having a viewing window therein, said body framesupporting a workpiece to be machined;

an apertured template mounted within said frame in fixed predeterminedrelationship with respect to said workpiece;

a lifting mechanism for lifting and lowering the body frame from and toengagement with the worktable to enable moving the positioning apparatusfor placing the workpiece at said selected location; and

a sighting mechanism for locating a selected template aperture which isin said predetermined relationship to said selected workpiece portion,including a pair of reflective surfaces that are spaced apart and aresupported by the body frame, one of the reflective surfaces beingvisible through the viewing window, with the other reflective surfacebeing optically aligned therewith and being movably supported within thebody frame to enable viewing the selected template aperture and meansfor moving said body frame to a position such that the selected templateaperture overlies said selected marked location on the worktable whenviewed through said sighting mechanism,

whereby said selected portion of the workpiece is positioned to bemachined.

6. The positioning apparatus of claim 5, wherein the other reflectivesurface is slidably mounted on supporting guide means, and has actuatingmeans operatively connected selected portion of a workpiece supportedthereon above a thereto such that an operator may move said otherreflective permitting relative movement between said worktable andpositioning apparatus, the supporting frame means being pivotallyconnected to the body frame to enable said winching assembly to lift thebody frame from the worktable to facilitate moving the positioningapparatus and workpiece to said selected marked location.

10. The positioning apparatus of claim 9, wherein the supporting framemeans is normally biased to a position disposed substantially whollywithin the body frame such that said body frame is in engagement withthe worktable.

* III

1. Positioning apparatus for use with a machine tool such as a drillpress, a milling machine, or the like, to enable placing a selectedportion of a workpiece supported thereon above a selected markedlocation on a worktable such that the portion of said workpiece can bemachined as required at said selected location, the positioningapparatus comprising: a body frame having a viewing window therein, saidbody frame supporting a workpiece to be machined; an apertured templatemounted within said frame in fixed predetermined relationship withrespect to said workpiece; a sighting mechanism for locating a selectedtemplate aperture which is in said predetermined relationship to saidselected workpiece portion including a pair of reflective surfaces thatare spaced apart and are supported by the body frame, one of thereflective surfaces being visible through the viewing window, with theother reflective surface being optically aligned therewith and beingmovably supported within the body frame to enable viewing the selectedtemplate aperture, and means for moving said body frame to a positionsuch that the selected template aperture overlies said marked locationon said worktable when viewed through said sighting mechanism, wherebysaid selected portion of said workpiece is positioned to be machined. 2.The positioning apparatus of claim 1, wherein the other reflectivesurface is movably mounted on supporting guide means, and has actuatingmeans connected thereto for enabling an operator to move said otherreflective surface over the template, thereby to visibly locate theselected template aperture.
 3. The positioning apparatus of claim 1,wherein the means for moving the body frame includes a lifting andlowering mechanism operable for effecting disengagement of a majorportion of the body frame from the worktable on which it is mounted. 4.The positioning apparatus of claim 3, wherein the worktable is providedwith a locking mechanism having pin means therein, the pin means beingoperative for engaging the selected template aperture to effect holdingthe workpiece substantially fixed in place.
 5. Positioning apparatus foruse with a machine tool such as a drill press or milling machine, forexample to enable placing a selected portion of a workpiece supportedthereon above a selected marked located on a worktable, such that theportion of said workpiece can be machined as required at said selectedlocation, the position apparatus comprising: a body frame supported onthe worktable provided on the machine tool, the body frame having aviewing window therein, said body frame supporting a workpiece to bemachined; an apertured template mounted within said frame in fixedpredetermined relationship with respect to said workpiece; a liftingmechanism for lifting and lowering the body frame from and to engagementwith the worktable to enable moving the positioning apparatus forplacing the workpiece at said selected location; and a sightingmechanism for locating a selected template aperture which is in saidpredetermined relationship to said selected workpiece portion, includinga pair of reflective surfaces that are spaced apart and are supported bythe body frame, one of the reflective surfaces being visible through theviewing window, with the other reflective surface being opticallyaligned therewith and being movably supported within the body frame toenable viewing the selected template aperture and means for moving saidbody frame to a position such that the selected template apertureoverlies said selected marked location on the worktable when viewedthrough said sighting mechanism, whereby said selected portion of theworkpiece is positioned to be machined.
 6. The positioning apparatus ofclaim 5, wherein the other reflective surface is slidably mounted onsupporting guide means, and has actuating means operatively connectedthereto such that an operator may move said other reflective surfaceover the apertured template and thereby visually locate the selectedtemplate aperture.
 7. The positioning apparatus of claim 6, wherein theone reflective surface is pivotally supported by the body frame toenable angular adjustment of the line of sight from the operator to saidone reflective surface.
 8. The positioning apparatus of claim 7, whereinsaid reflective surfaces are mirrors.
 9. The positioning apparatus ofclaim 5, wherein the lifting mechanism includes a winching assembly andsupporting frame means which are operable to engage the worktable forpermitting relative movement between said worktable and positioningapparatus, the supporting frame means being pivotally connected to thebody frame to enable said winching assembly to lift the body frame fromthe worktable to facilitate moving the positioning apparatus andworkpiece to said selected marked location.
 10. The positioningapparatus of claim 9, wherein the supporting frame means is normallybiased to a position disposed substantially wholly within the body framesuch that said body frame is in engagement with the worktable.